I think it would be great if Locus supported extruded polygons (3D) in KML overlays, and along with that, support bird's eye navigation on a user configurable angle and distance from current location. It would be similar to Garmin's 3D buildings in cities. Maybe make the view angle select-able in 5, 10, or 15 degree increments, and the zoom level would be your distance. This would be a killer feature in my opinion.
Your idea is heavily related to this one: http://help.locusmap.eu/topic/3d_maps_by_using_srtm_files